Long-term outcome after normal myocardial perfusion imaging in suspected ischaemic heart disease
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ABSTRACT

INTRODUCTION: Ischaemic heart disease (IHD) is the leading cause of mortality in the Western world. Therefore, to focus on those at risk of having IHD while at the same time avoiding unnecessary patient concern, it is important to have diagnostic tools capable of refuting an IHD diagnosis. Within the past 30 years, myocardial perfusion imaging (MPI) has been used increasingly to detect myocardial perfusion defects. MPI is a safe and non-invasive method with a sensitivity and specificity of > 90%. The aim of this study was to evaluate the long-term prognostic outcome after a normal MPI. 
Methods: The study population comprised patients referred for MPI from one single department of cardiology with invasive facilities, from 2008 to 2009. The patients' demographics and the results of the MPIs were collected from their medical records. Only patients without known IHD and with a normal MPI were included. After a follow-up period of 7.8 years (range 6.8-8.8 years), a retrospective database search was performed. The major outcomes were all-cause mortality, cardiac events defined as nonfatal myocardial infarct or coronary revascularisation by percutaneous coron-ary intervention or coronary artery bypass grafting. 
Results: The risk of a cardiac event or death following a normal MPI was 9.6% during long-term follow-up, with an estimated annual death rate of 1.4% per year (95% confidence interval 0.8-2.5%). This was not different from the background population. 
Conclusion: A normal MPI predicts a favourable long-term prognostic outcome. 
Funding: none.
 Trial registration FSEID-00002257.